Process of making hollow propellers



Feb. 5, 1946. A. A. HANDLER PROCESS OF MAKING HOLLOW PROPELLERS Filed July 18, 1958 @Sheets-Sheet l lo i Mmk 9 mm 6 w wk ll 11' flilnunn lllll T Q WAWA AJ 0 f p lllilillllall W H wfli Feb. 5, 1946. A. A. HANDLER PROCESS OF MAKING HOLLOW PROPELLERS a Sheets-Sheet 2'" Filed July 18, 1938 2 muL wN 966 on r ATTORNEYJ Feb. 5, 1946. A. A; HANDLER PROCESS OF MAKING HOLLOW PROPELLERS Filed July 18, 1938 s She et sSh eet s INVENTOR. 17L f/FED 14. Hfl/VDLEE.

ATTORNEYQ Patented Feb. 5, 1946 raocsss or MAKnvo'noLtow PROPELLERS Alfred A. Handler, Cleveland, Ohio, assignor to Aluminum Company of America, Pittsburgh. Pa., a corporation of Pennsylvania Application July is, 1938, Serial No. 219,11 1

17 Claims.

This invention relates to the art of metal work'- ing, and more particularly to a process of forging airplane propeller blades, and the blades produced thereby. v

Many airplane propeller blades have heretofore been made of aluminum or other light metal alloy stock. Light'metal alloys are particularly well suited for such propellers because they provide the nece'mary strength and airfoil section with a minimum weight, which is desirable not only from the standpoint of total weight of the airplane; but also in reducing the centrifugal loads.

The most successful metal airplane propeller blades heretofore made have been those made of light metal alloys and fabricated in accordance with my prior Patents Nos. 1,957,499, 2,044,293, 2,044,294 and 2,044,295. These blades have been used in large quantities and have proven extremely reliable. Many efforts have been made,

however, to further reduce the weight of propeller.

blades in proportion to their length and airfoil section without sacrificing the necessary strength to carry the various centrifugal, thrust and vibratory loads to which the blades are subjected.

The present invention has as its principal object the reduction of the weight of metal propeller blades in proportion to their size while maintain]- ing the necessary strength, durability, fatigue resistance and uniformity. I The principal feature of the presentinvention" consists broadly of forming a hollow blank tapering generally from the end which is to form the hub to the end which is to form the tip of the,

blade, and with suillcient cross-sectional areaat each point in its length to provide the necessary metal for the finished blade and with non-uniform wall thickness, and forging or pressing the blank to blade form with one or two thick portions of the wall of the blank forming one or both edges of the blade. Preferably the thick wall portlons' are formed by forging laterallyprojecting ilns along opposite sides of the blank, after which the greater volume of metal at the edges thanat the flat faces of the blade.

During the flattening operation the metal immediately adjacent the internal hole in the blade is bent through relatively gradual and easy curves,

since the opening does not 'extend'to the edges of the blade. As a consequence, the stresses imposed on the metal are maintained substantially uniform around the blade, and at all points are maintained well within the allowable limits of work-I ing stresses.

Non-uniform working orstressing of the metal larger grains tend to assimilate, and grow at the expense of, the smaller grains. v Accordingly, the p more uniform the amount of working to which the metal is subjected, the less the grain size conmainbody of the blank is hollowed outin any suitable manner, and the blank is finally pressed or forged to final form, the internal hole being flattened out to conform substantially to the external contour of the finished blade forging. It will be understood, however, that the invention in its broader aspects is not concerned with the particular way of making the hollow blank. During the final-pressing or flattening the metal in the laterally projecting this or thick wall portions:

is pressed into the desired shape of the leading and trailing edges of the blade, and provides a trast, and the less grain growth will occur in the finished forging. Where excessive grain size contrast exists, as at the junction of zones in the metalwhich have received substantially diflerent amounts of working, the more rapid grain growth produces an area of excessively large grains which constitute an area of, weakness in the finished blade.

.All of'these defects resulting from unequal or non-uniform working, of the metal in different parts of the blade are avoided or minimized in the present invention by maintaining the internal openings spaced a greater distance. from the outside edge of the metal at the parts-which are to form the edges of the blade so that the working of the metal in the flattening of the blank is sub,- stantially uniform around the internal opening.

The present invention also includes a number of other fabricating steps which are more particularly useful in connection with the principal feature of this invention, but which are also useful separately or in other processes of making propellers or similar articles. The blank is preferably formed from a billet which has been rolled or extruded. which is first tapered towards the end which will eventually be the tip end of the. propeller blade. In this tapering at least a portion of the billet acme-4s 3 provide the necessary metal and arrangement thereof to form the leading and trailing edges in the finished blade shown. It will be understood, of course, that the relative positions and dimensions of the fins 5 and 6 will vary with the blade design. The fins 5 and Gare worked out laterally from the tapered portion 3 of the blank shown in Figure 2, leaving a central roughly conical portion I. When the blank 2 is made in accordance with the preferred process as explained above,

7 the longitudinal fiow lines of the conical portion 3 are simply spread out laterally without being broken or seriously distorted in the formation of the fins 5 and I3.

I prefer to form these fins by hammering or pressing with dies such as illustrated diagrammatically in Figure 24. As shown, mating dies 8 and 9 are provided with recesses I II smaller than the corresponding diameter of the coned portion 3 of the blank. The dies are also formed with recesses II and I2 shapedto form the fins 5 and 5, so that metal spread laterally from the portion 3 of the blank is forged or pressed into the fins.

The blank as shown in Figure 3 is thenformed with an internal opening. In the embodiment shown this 'is accomplished by boring a substantially cylindrical hole I3 from the hub end of the blank through the greater portion of the length of the blank and terminating in a substantially conical hole I4 which stops short of the tip end of the blade as shown in Figure 8. It will be understood, however, that the internal opening may be made in any suitable manner. For example, the blank may be made'smaller in dimensions than illustrated in Figure 3 and the hole may be formed at least partially by piercing as disclosed in my prior Patent No, 1,957,499 with the remainder of the hole, if necessary, finished by boring or in any other suitable way.

At the conclusion of this operation the blank has the form illustrated in Figures 8 to 16, inclusive, with the hollow substantially cylindrical portion 4 and the hollow conical portion 1 carryin the fins 5 and 6. 1

In the preferred embodiment oi'this invention the shank end of the blank is next swaged or otherwise worked from the substantially cylindrical hollow portion 4 to the shank I5 illustrated in Figure 1.7. I This operation is preferably accomplished by swaging as illustrated diagrammatically in Figure 25. As shown a pair of mating dies I6 and I1 are provided with oval apertures designed to receive and forge the hollow portion 4 into an oval shape in one direction.

The blank is then turned 90 and again struck by the dies I6 and I1 forcing it to an oval form in the opposite direction. This operation is con-- tinued with one or more sets of dies'until the walls of the hollow cylindrical portion 4 are reduced steps, making the grain refinement and working of the metal more uniform throughout the fin i moved. In the embodiment illustrated the shank substantially to the diameter and thickness of the shank I5 as illustrated in Figures 17 to 22, inclusivef Other working operations, suchas rolling, may be substituted for the swaging, if desired.

It will be apparent that this operation permits the forming of a straight hole extending into the blank from the hub end which is larger in diameter than the hole in the finished shank. This permits the removal of the maximum amount of metal from the blade portion without destroying the desired proportions of the finished blade and without sacrificin the strength of the shank. At the same time, this operation thoroughly works and refines the metal of the shank and hub portions, which were unworked in the blade forming end I5 is then upset to form a flange I8 and where desired a bearing ring I9 may be secured upon the shank by the upset flange 18in accordance with the process disclosed in my prior Patent No. 1,995,451. It will be understood that the flange may be upset either before or after the final forging of the blade.

The entire blank as illustrated in Figure 17 .is

then placed in pressing or forging dies and is fiattened through the blade portion substantially to the contour illustrated in Figures23 and 26150 33,

inclusive. During the flattening operation the,

fins 5 and 6 formed by the blade portion are pressed into the trailing and leading edges 20 and 2I, respectively, of the blade. The hollow shank portion I5 is partially flattened as illustrated in Figures 27 and 28 and the edges thereof merged smoothly into the edges 20 and 2| formed from the fins 5 and 6. In the same operation the blank is preferably given the desired twist or pitch and in the design of blade shown one side is flattened to form the flat side 22 of the blade and the opposite side is suitably shaped to form the contour face 23 of the blade. g

It will be apparent that in the swaging operation to form the shank and I5 the longitudinal fiber structure orfiow lines of the hollow cylindrical portion 4 are simply bunched or pressed so that they remain in substantial conformity with the contour of the finished shank portion I5. Likewise, in the final pressing or forging of the blank to shape, the metal of the hollow shank portion I5 and the hollow conical portion 1 is simply bent into the desired contour and at no point is themetal bent through a sufliciently sharp angle to unduly stress the metal. The sharper portions of the edgesv of the blade at the leading and trailing edges 25 and 2| are formed from the solid fins 5 and 6 so that it is unnecessary to bend thehollow blank portion throught he sharp angles required to form these edges. Accordingly in this operation the metallic structure produced in the blade by the previous forging operations is not injured.

In the final forging or pressing the blank is preferably forged slightly smaller with the consequent formation of a small fiash around the leading and trailing edges of the blade. By reason of the arrangement of the metal into the proper position and with the proper cross-sectional area of. metal to form the finished contour at each point throughout the length of the blade, the flash is substantially uniform in depth at all points and is maintained of extremely small dimensions in order to avoid any possible interference with the metallic structure developed by the previous operations.

In the carrying out of the final forging or pressin of the blade a deformable material, when desired, may be maintained in the internal opening to exert a pressure against the walls of the opening andprevent any tendency of collapse. Sand or similar material may be employed and removed after this operation has been completed. Likewise the internal opening may be filled with compressed air or gas to exert a pressure against the mounted ina hub.

The finished blade shown in Figure 23 has the; usual propeller blade shape with the substantially 4 V V l walls of the internal opening. I have found, however, that this forging or pressing operation may be successfully carried out on most designs of blades without any core material within the internal opening andwlth the same open to atmosphere, Possibility of collapse of the walls of the blade i greatly reduced, if not entirely eliminated, i

by the formation of the fins 5 and Sprior to the flattening operation. 7 i

Following the operations described, the blade 7 forging is completed in an desired way, usually by trimming, sizing and heat treating. The blade forging is then given any desired finishing opera tions, such as machining, grinding and Polishing, to'bring it tothe exact dimensions and surface characteristics desired,

cylindrical shank portion l5 merging into the blade portion, the latter having the relatively fiat sides oriaces 22 and Hand the leading and trail in'g edges 2 I and respectively which diverge from the shank to an intermediate point and converge to the tip end of theblade. Asfwillbe apparent from Figures 23, 28 to 32, incluslvathe walls of the blade are substantially thicker at the leading and trailing edges than at the side faces" by reason of the formation of these edges from the fins land 8; It will likewise be apparent that when the blade portion isifiattened in the final forging operationthe perimeter of the hole in the 7 blade portion remains substantially constantexcept as it may be diminished by any slight thickening of the walls and consequent flowing of the metal into the hole in the final forging operation, I

whereas the perimeter of the hole in the shank portion is substantially reduced byreduction of the shank portion in the swagingoperation or the like. 7 5

in the manufacture ofbladesfrom aluminum alloy or other light metal alloy, it is also readily,

For example, bladesv adaptable to other metals.

may be made or iron, steel, copper and its alloys, such as brass and bronze, and nickel alloys. Ina

be forged or rolled may? fact any metal that can be worked into blades by this process. I Although I have described a specific example,

of my invention it will be understood that many? variations and rearrangements of the-steps may be resortedto without departing from the'scopel of the invention. For. example, the various operations for forming the hollow blankoi non-' uniform wall thickness may be combined or rearranged in any desired way. Similarly the various novel features of the invention, while most valuable when used. together, are also "useful.

separately and in other combinations, Accordingly I do not wish to be limited except by the 60 following claims. I claim:

1. The process oi making apropeller blade comprising forging at least a portion of the length of .a solid billet into a substantially conical form tapering toward the tip end of the blank, forging a radially projecting fin through at least a portion of the length of the blank forming an internal opening substantially round in cross sectlon in the blank and flattening the blank by a 1 pressure operation so that said radially projecting fin'is formed into one of theedges of the" blade.

2. The process of making a propeller'blade comprising forging at least a portion of the length of a solid billetinto a substantially conical shape and i then ready to be V 11o While I find this invention to be most useful tapering toward the tipend oi the blank, forging a pair of radially projecting fins through at least a portion ot'the length ofthe blank, form- 6 ing an internal opening substantially. roundin cross section in the blank and flattening the blank by a pressure operation so that said, radiallypr'ojecting'fins are formed into the edg'es of the blade. 0

3. The process making a propeller bladef V atleasta part of thelength V 1 of asolld billet into a roughly conicalxshape,

" comprising forging tapering toward the tipend of the blank, forging a radially projecting fin upon the blankex- 1 tending from the tip end-through aportlon of thelength, forming an internal openln'gin the blank extending f'rom the hub and throughat least a portion of the length oibthe: blank and tapering in diameter toward the 'tipsend-, offthej' V and flattening the blank by, a pressure] operation so that said finis'formed into'oneof the edges of the blank, V V

H4. The process of making a comprising rolling a solid billet of 'blade through substantially; the

ical portion into blade shape. 7

comprising; forging one end oi. a solid circular in cross-section through atleastapart of thelength of the conical portion ofsaid blank On which said-fin fie formed, to produce a blank having? a hollowhflnnedzportionifwith the metal distributed iii-"successive transversesections'rimzq amounts substantially. proportional .to the' metal distributloninithe corresponding portions ,oi'ith finished blade,

same, and-tofbring.theeexteli 'fl lfi 01 1 8 5, I

1 portion substantially into} aiine-z hollowf finned mentwith the surfacesof said fin.

comprising forging one end of said blank. into the conical portion on which said fin is formed, to produce a blank hav-' ing a hollow, finned portion with the metal dis tributed in successive transverse sections in amounts substantially proportional to the metal. distribution in the corresponding portions oi the finished blade, and flatteningsaidblank through 1 at least said hollow finn'edportion to flattensaid. circular opening" withoutjcompletely closing sh i exterior surfaces of the into aline-' same, and to bring the hollow finned portion substantially ment with the surfaces of'said an,

propeller blade.) metal to form 26 a substantially conical portion tapering toward the tip .end of the bladepiormingl'a blindopen i j insnx endingrinwardly from thehubend ofthe r r Y v entire :conlcal I portion and'by aforging operation flattening the hollow blank so formed to'p're'ss the hollowcon-l 5. The process of making a propeller blade cylindricalv metal billet into a] substantially conical I form tapering" toward the tipl'end r the blank, ;forg- 8 theblankto form a fin extendinglongitw. dinally along the ,conicalportion andhaving at, cross-sectionallcontour approximating'the crosssectional contour of an edgeofzthe. finished 1 blade, forming .an internal opening substantially an fla i n ns sl b n fli h at least} saidyholiom finned portion to flattenbsaid? circular opening without] completelygclosingythe 7. The process of making a propeller blade comprising forging one end of a solid cylindrical metal billet into a substantially conical form tapering toward the tip end of the blank, forging the blank to form a fin extending longitudinally along opposite sides of the conical portion and around the tip end of the blank and having a cross-sectional contour approximating the cross-sectional contour of the edges and tip of the finished blade, forming a blind internal opening substantially circular in cross-section extending from the hub end of said blank into the conical portion on which said fin is formed, to produc a blank having a hollow, finned portion with the metal distributed in successive transverse sections in amounts substantially proportional to the metal distribution -in the corresponding portions of the finished blade, and flattening said blank through at least said hollow, finned portion to flatten said circular opening without completely closing the same, and to bring the exterior surfaces of the hollow finned portion substantially into alinement with the surfaces of said fin.

8. The process of making a propeller blade comprising rolling one end of a solid cylindrical metal billet having longitudinal fiow lines into a substantially conical form tapering toward the tip end of the blank so as to gather said longitudinal flow lines into conical shape, forging the blank to work out a fin extending longitudinally along the conical portion and having longitudinal flow lines and a cross-sectional contour approximating the cross-sectional contour of an edge of the finished blade, forming an internal opening substantially circular in cross-section through at least a part of the length of the conical portion of said blank on which said fin is formed, to produce a blank having a hollow, finned portion with the metal distributed in successive transverse seceions in amounts substantially proportional to the metal distribution in the corresponding portions of the finished blade, and flattening said blank through at least said hollow, finned' portion to flatten said circular opening without completely closing the same, and to bring the exterior surfaces of the hollow finned portion substantially into alinement with the surfaces of said fin while maintaining a longitudinal flow line structure in said fin and said flattened hollow portion.

9. The process of making a propeller blade comprising forging one end of a solid cylindrical metal billet into a substantially conical form tapering toward the tip end of the blank, forging the blank to form a fin extending longitudinally along the conical portion and having a cross-sectional contour approximating the cross-sectional contour of an edge of the finished blade, forming an internal opening substantially circular in cross-section and tapering in diameter toward the tip end of the blank through at least a part of the length of the conical portion of said blank on which said fin is formed, to produce a blank having a hollow, finned portion with the metal distributed in successive transverse sections in amounts substantially proportional to the metal distribution in the corresponding portions of the finished blade, and flattening said blank through at least said hollow, finned portion to flatten said circular opening without completely closing the same, and to bring the exterior surfaces of the hollow finned portion substantially into alinement with the surfaces of said fin.

10. The process of making a propeller blade comprising forging one end of a solid cylindrical metal billet into a substantially conical form tapering toward the tip end 01' the blank, forging cular in sectional contour, forming an internal opening substantially circular in cross-section through at least a part of the length of the conical portion of said blank on which said fin is formed, to produce a blankhavin'g a hollow, finned portion with the metal distributed 1 in successive transverse sections in amounts substantially proportional to the metal distribution in the correspondingportions'of the finished blade, and fiattening said blank through at least said hollow,

finned portion to flatten said'circular opening without completely closing the same, and to bring the exterior surfaces of the hollow finned portion, substantially into alinement with the surfaces of said fin.

1 1. The process of making a propeller blade comprising forging a solid elongated metal blank to form a' fin extending longitudinally therealong' and having a cross-sectional contour approximating the cross-sectionalcontour of an edge of the finished blade, forming an internalopening substantially circular in cross-section through at' leasta part of the length of said blank on which said fin is' formed, and flattening said blank} through at least said hollow, finned portion to flatten said circular opening without completely closing the same, and to bring the exterio sur-,'

faces of the hollow finned portion substantially into alinement with the surfaces of said fin.

12. The process of making a propeller bladed comprising-forging a solid elongated metal blank having a body portionand a thickened portion extending longitudinally along one side oflthe.

body portion and projecting therefrom in aradial direction, forming a'longitudinal opening in said body portion through at least a part of the length thereof on which said thickened portion i formed, said Opening being of such diameter as to leave the wall of said body portion on each side of said solid thickened portion with a radial thickness.

" less thanthe circumferential length of the Junction of said solid thickened portion with said body portion, and forging said thickened portion. into one of the edges of the finished blade and bending the walls of said body portion toward each other to flatten said opening without completely closing the same and to bring the exterior surfaces of saidwalls substantially into alinement with the surfaces of said edge.

13. The process of making a hollow propeller blade comprising forging one end of a olid metal billet into a substantially conical form tapering toward the tip end of the blank, forging the blank to form a solid thickened portion projecting in a radial direction from the conical portion and extending longitudinally along opposite sides of the conical portion and around the tip end of the blank,forming an opening extending longitudinally into the blank from the hub end thereof and through at least a part of the finned length and terminating short of the tip end, said opening having a diameter exceeding the thickness of said thickened portion and tapering in diameter toward the tip end of the blank, and flattening said blank through at least said hollowfinned portion to form said thickened portion into the edges and tip of the propeller blade, and to bring the exterior surfaces of said hollowportion sub- 1 Santana f'mto! alignment with the surfaces or said edsesandtipr 14 The; process ofl makingl a propellerv blade] comprising forging one end of; a solid cylindrical metal billet intoasubstantiallv conical,torm ta- 2,894,445 7 I g i "end of asolidmetalblllet, forging the 'blankto iorm a iin extendinglongitudinally along the taperlngportion and having a cross-sectional con tour approximating the v cross-sectional contour 01 an ed e of the finished blade, forming a 1011- pering" toward the tip endot the b1an k, forging.

1 the blank to mm a solid thickened portion ex- 7 1 1 tendingilongitudinallyalong the conical portion, land projecting therefrom in-a-f radial direction, forming an internal ,opening substantially circuilar in cross section through at least a partner :the leng'thl of'the conical .portion of said blank 3 on whichsaid thickened portion is formed, to, pro-- g duce a. blank having 'aihollow portion with asolid projection with the metal distributed in successivev transverse sections in amounts substantially,

v hollow, finned portion with the-metal distributed in successive transverse sections in amounts: substantially proportional, to the metal distribu-;

proportional to the metal distribution intthecor-,

respondingf portionsvpf' the finished; blade and fflatteningi'said blank. to form saidthickened pon tion into one or the edge of the finished blade and bending the walls otsaid hollow portion toward each otherto flatten said opening without completely closingthefsame and-to bring the e'x-- terior' surfaces ofsaid walls substantially' into alinem'ent with the surface'sof said edge.

15. The ,processiofmaking a -propeller blade comprising'xforging, one end of, a solid cylindrical smetal billet'intoa substantially u-conical form ta-*. pering toward the tip end'; of v the blank, forging the blank to .form a solidthickened portion ex ten'di'ng longitudinally along ,thelconic al portion a andpr'oj'ecting therefroinfin a radial direction forming" a blindinternal opening substantially v circular in" crossse'ction extendingiiro n the hub; end ot'said blank",intoithe-conical portion on which said lthickened portion .is formed, t o pro? ducea blank'having a hollow portion'with a. solid 1 projection with the'metalldistributedfin successive transverse sectio'n's 'inv amounts substantially proportional tothe metal. distribution in the cor flattening'said blank to' form said thickened pqr; tion-"into onej'o'f theed'ge's of the finished "blade and. bending th'ewalls' of said hollow portion toward: 'e'achfotherjto flatten saidfopening without completelyclosing-thesame andnto' bring the ex-v teri'or surfaces of saicl wallssubstantially into aline'mentwith the surfaces of said edge; s

h jprocess of makin a pr e ler blade comprising ibrging a tapermg'pornon' on one responding" portions of{ the-fizfished blade and} g-itudinally extending internal opening through at least a part of the length'of the tapering portion of. said blank on which-said fin isformed; :said opening beingJ-of. such sizein cross-section; as to leave the wallsof said blank 0n oppositesid of said fin with aradial thickness less than" the circumferential length of the junction of said fin with said blank, to producea blank havinga tion in the; corresponding portions of the finished blade, and fiatteningsaid-r blank throughat least .i

, said hollow, finned portion to flatten said internal openinguwithout completely closing the same 7 and to-bring -the exterior surfaces of the hollow l finned portions substantially into alinement with the surfaces ofsaidfin.

17. The process of making a section as to leave the walls ofsaid blank on opposite sides of said fin with a radial'thic'kness less than the circumferential length of the junc-x tion of saidfi n with said blank, to produce a blank having a hollow, finned portion -'with the metal distributed in successive transverse sections in amounts substantially.p oportional to the metal distribution in the corresponding portions of the finished blade, and flattening said blank through at least said hollow,ifinned portion 7 to flatten said internal opening without; completely closing the,same,-and tojbring the exterior surfaces of the hollow finned portion substantially into alinement with the surfaces of :said 1111..

v ALFRED A. HANDLER. 

